1. Field of the Invention
The present invention relates to novel amides useful as components of detergents for the skin and hair, as emulsifiers in cosmetic compositions, or as conditioning agents. The invention also relates to methods for preparing the amides as well as detergent compositions containing the amides.
2. Description of the Related Art
Conventionally, surfactants such as alkyl sulfates, polyoxyethylene alkyl sulfates, and alkylbenzene sulfonates have been used as detergents and emulsifiers. However, most of them have the problem that they give relatively strong stimulation to the skin during use. Therefore, certain surfactants which are mild to the skin, e.g., alkyl phosphates and acylated amino acids, have come to be used as bases or emulsifiers incorporated in hair care or skin cosmetic compositions or as detergents for the skin, etc.
As consumer demand has become diversified and quality-oriented, improved properties are required for these products, including not only mildness to the skin but also good latherability and a pleasant sensation to the skin. The surfactants mentioned above do not necessarily satisfy such needs.
A variety of quaternary ammonium salts, which are categorized as cationic surfactants, are used as conditioners for the hair and finishing compounds. Quaternary ammonium salts, however, have proven useful only within very limited fields because they have insufficient latherability and are not necessarily mild to the skin. Thus, they are not used as bases or emulsifiers in hair-care or skin cosmetic compositions, nor as detergents for the skin, etc.
The present inventors found that 2-hydroxypropanediamine derivatives have excellent latherability and are mild to the skin, and they previously filed a pertinent patent application (WP95/01955). Nevertheless, compounds having better properties are still desired.
Under the above circumstances, the present inventors conducted extensive studies and found that the new amides represented by formula (1) described hereinbelow provide a pleasant sensation to the skin without giving irritation to the skin and have excellent latherability and emulsion stability. The present invention was accomplished based on this finding.